Assembly structure for making integrated circuit chip probe cards

ABSTRACT

This disclosure proposes an assembly structure for building probe cards to test square integrated circuit chips. The test probe card assembly structure has one or more wings located at 90° angles to each other upon which probes are laid in a parallel manner for attachment to a probe card. This allows 10 construction of the probe card so that probes touch contacts directly. The probe tips do not touch the contacts at an angle θ, called the fan out angle. The probes also do not differ in their inclination angles β. As a result, the force at which the many probe tips touch the contacts is relatively constant throughout. In addition, the probe tips are less likely to scrub past the surface of the contact onto the insulation surface of the chip and in doing so damage it. The test probe card assembly structure also contains an epoxy groove, which controls epoxy flow so that the position of the probes stays aligned in the correct plane. The epoxy groove also prevents variance in beam length. An alternative embodiment of the present invention can make probe cards for simultaneously testing multiple chips and includes a probe card for testing multiple chips.

FIELD OF THE INVENTION

This invention relates generally to probe cards used to test integratedcircuit chips. More particularly, it relates to the assembly structureused to manufacture such probe cards.

BACKGROUND OF THE INVENTION

In a typical integrated circuit (IC) chip, the input, output, powersupply and other terminals of the circuit are formed by metalizedcontacts, usually deployed along the margins of the circuit pattern. Theoutline of the chip is often square, and the marginal locations of thecontacts depend on the circuit configurations and the available marginalspace. In some instances the contacts may lie in a uniform row or rowsalong the margins.

For the purpose of testing any type of integrated circuit patterns,before the application of leads to connect the contacts to othercomponents, various types of test probe cards have been developed. Themost commonly used probe card consists of a printed circuit board havinga circular opening or port to provide access to contacts on an IC chip.This opening is surrounded by conductive probes connected to terminalson the card which, in turn, are connected to test equipment appropriateto the circuit. The number of probes in the opening determines themaximum capacity of the probe card.

Structures used to assemble typical test probe cards consist of a basecontaining a downward-pointing funnel. A number of probes 22 are laid ina circular manner around the base with the probe tips pointing downtowards the center of the funnel, as shown in FIG. 1A. Due to thecurvature of the funnel surface even probes lying next to each other,e.g., probes 22A and 22B at a fan out angle θ=0 have differentinclination angles β, as indicated in FIG. 1B. In general, probes at afan out angle q will also have a different inclination angle β.

After probes 22 are adjusted on the funnel plane, a layer of epoxy islaid over them, as shown in FIG. 3. The epoxy is then hardened byheating and the structure of probes and epoxy is attached to a planarinsulation card having a printed circuit and a port.

Since the probes are attached to the probe card in a circular manner,they touch contacts 106 located on an IC chip 105 at different fan outangles θ, as illustrated in FIG. 2. A probe located in the center of arow of probes touches a contact located in the center of a row ofcontacts directly, at 0°. However, a probe located at the end of a rowof probes requires a steeper fan out angle θ to reach a contact locatedat the end of a row of contacts, in the corner of the chip.

Since the probes are laid on an inclined assembly structure with theprobe tips pointing downwards, as shown in FIG. 1A, they will form aninclination angle θ with the plane of the IC chip. Since the probes arelaid on a non-planar surface, the inclination angle of each probe willvary greatly (see FIG. 1B). In general, probes at the end of the rowwill have a smaller inclination angle than the probes at the center ofthe row. The disparity in the inclination angles at which the probes arelaid will cause the force between the probe tips and contacts of the ICchip to vary over a wide range.

This disparity also causes deformation of the probe tips when they areplaced in the holes of the Mylar sheath. The bend angle of the tipchanges and alignment of the probe tips suffers. The Mylar may also bedislodged or deformed by the probe tips, which may also cause alignmentto suffer. Often if the inclination angles of the probes differ, theprobe tips may even pop out of the Mylar holes, again causing problemswith tip alignment and planarity. These events may cause differences inthe force at which the probe tip touches the contact and prevent uniformscrub length.

When the probes touch the contacts on the chip, the probe tips scrub thecontact surfaces to remove the oxide film, and thereby establishelectrical contact, as shown by scrub mark 100 of FIG. 2. Disparity inthe inclination angles of the probes will cause non-uniform scrub marks.In addition, because of fan out angles, some of the angles at which theprobes touch the contacts are quite large (˜25-45°), and the scrubbingmotion causes the tips to go beyond the contacts to invade the surfaceof the chip, as shown by scrub mark 102 of FIG. 2. These scrub marksdamage the functionality of the IC chip by destroying the insulatingpassivation layer.

Since all of the contacts in an IC chip lie in a common plane and mustbe simultaneously engaged in order to carry out testing, it is essentialthat all probe tips lie in a plane parallel to the common IC plane.Consequently, a fundamental requirement for a probe card isplanarization of the probe tips. After the probes have been adjusted toassume their proper angles, an epoxy is poured over the array of probesso as to embed them at their assigned angles and planes in the epoxy, asillustrated in FIG. 3. The epoxy is not contained, however, and oftenflows around the probes, dislodging them. Misalignment of the probesoccurs so they are no longer at the correct angles or in the correctplane, as seen in FIG. 4. Thus a uniform contact force becomesimpossible to achieve.

Because the epoxy flow is uncontrolled, it may run down the length ofthe probe, as shown in FIG. 3. The result is variance in the amount ofprobe exposed, also called beam length and indicated by reference L. Onewill thus get some probes with beam lengths L that are shorter or longerthan others. The force at which a probe touches a contact on an IC chipdepends to a large extent on the beam length and thus uniform beamlengths are crucial.

With a view to providing a test probe assembly that has uniform andconsistent scrubbing characteristics, the Evans U.S. Pat. No. 4,599,599discloses a structure in which a circular array of probes, all lying ina horizontal plane, are supported on a mounting ring surrounding acircular port in a card. The probes converge toward the central regionof the port below which is the chip to be tested, with the slope anglebetween each probe tip section and the surface of the chip uniform.Despite the fact that this probe card minimizes the problem of probesaligned on different planes, it still retains the fan out angles forprobes touching contacts at the corners of the chip and the resultingscrubbing problem.

The Evans U.S. Pat. No. 4,719,417 discloses a structure for amulti-layered test probe assembly, which features two radial arrays ofprobes to test an exceptionally large number of contacts on an IC chip.It also retains the fan out angles for probes touching contacts at thecorners of the chip and the resulting scrubbing problem.

Another consideration in the manufacture and use of probe cards is thethroughput of the testing step. The testing step often constitutes abottleneck in the manufacturing process. Increasing the throughput of aprobe card would increase the number of chips made and therefore reducethe cost per chip. Throughput can be increased by testing a number ofchips simultaneously while the chips are connected in the wafer.

OBJECTS AND ADVANTAGES OF THE INVENTION

Accordingly, it is a primary object of the present invention toconstruct an assembly structure for probe cards such that the probes cantouch contacts on an integrated circuit chip directly at 0°; i.e.eliminating the fan out angle or making it negligible. This will resultin a decrease in the number of contacts and IC chips damaged byscrubbing motions of the probe tips. It is an additional object of theinvention to remove variances in the inclination angle β, which willremove the variances in contact force between the many probe tip andcontact connections. Removal of the different inclination angles alsoprevents dislodgment or deformation of the Mylar sheath and the probetips. It is an additional object of the invention to construct a probecard so that the probes are all located in the same plane by use of anepoxy groove, which prevents the epoxy layer from flowing and thusdislodging the probes after they have been positioned. Preventing theepoxy groove from flowing down the probes also allows control of thebeam length, which is crucial for determining the force at which theprobe tips touch the contacts of an IC chip. Probes located on a singleplane will also remove the resulting variances in force between the manyprobe tip and contact connections. It is a further object of the presentinvention to provide these same benefits to a multi-layered probe cardconstructed in an analogous manner.

Another object of the present invention is to provide a probe cardcapable of testing multiple chips simultaneously and an assemblystructure capable of making such probe cards.

SUMMARY OF THE INVENTION

These objects and advantages are attained by a test probe card assemblystructure used to construct probe cards to check integrated circuitchips before terminal leads are applied to the contacts thereof whichare deployed on the chip in a common plane. The assembly structure has abase with a block attached to one side. A wing, having a planar faceinclined towards the block, is attached to the same side. Two or morewings are attached at 90° angles to each other, depending on the natureof the IC chip and its contacts. The probes are laid on the wing in aparallel manner and at a constant inclination angle. The planar face ofthe wing has an epoxy groove to insure that the epoxy layer used to holdthe probes in place does not flow. Epoxy flowing can disturb theparallel nature and plane of the probes, as well as vary the beamlength. The planar face of the wing also has a tape groove to receivedouble-sided adhesive tape which is used to hold the probes in place,again preserving the parallel nature and plane of the probes. In thepreferred embodiment, the wing can consist of two parts. One part is asupport block, which has the planar face. The second part is a probepositioning element, which is a removable incline used to secure asheath for keeping the probe tips in place. The sheath is commonlyconstructed of Mylar. A probe alignment control element, commonly a ringwith at least one raised section, is placed over the epoxy layer to holdit and the probes in place. The probe alignment control element isstopped at a certain position in order to control the thickness of theepoxy layer. this is achieved by guiding members, commonly pins attachedperpendicular to the base, in conjunction with recesses on the probealignment control element. This assembly structure can be used toconstruct both single and multi-layered test probe cards.

The present invention also includes an embodiment which can make probecards capable of testing multiple chips while the chips are stillconnected in wafer form. The chips tested are arranged along a diagonalon the wafer and the probes extend in a direction perpendicular to thediagonal. Since the chips are square and arranged in a diagonal fashion,the contact pads along the perimeter lie in a zig zag path. The probesare oriented in a corrugated fashion such that the angle β is the samefor each probe, despite the fact that the contact pads lie in a zig zagpath. Also, the beam length of the probes is made the same for eachprobe by making the region where the probe is bonded vary with the samezig zag path as the contact pads.

DESCRIPTION OF THE FIGURES

FIG. 1A is an isometric view of a prior art test probe card assemblystructure, with the probes aligned in a circular manner.

FIG. 1B is an isometric view of a prior art test probe card assemblystructure, with the probes having different inclination angles β.

FIG. 2 is a top plan view of probes attached in a circular manner to aprior art test probe card testing a square integrated circuit chip atdifferent angles.

FIG. 3 is a cross-section of a probe, held in place by an epoxy layer,being mounted on the prior art test probe card assembly structure.

FIG. 4 is a cross-section of three probes held in place by an epoxylayer in the prior art method.

FIG. 5 is an isometric view of the preferred embodiment of a test probecard assembly structure in accordance with the invention, with probepositioning elements and guiding mechanisms.

FIG. 6 is a lower left isometric view of the probe alignment controlelement with four raised sections and four recesses.

FIG. 7A is a cross-section of a probe being mounted on the preferredembodiment of a test probe card assembly structure in accordance withthe invention.

FIG. 7B is a top plan view of probes being mounted on the preferredembodiment of a test probe card assembly structure in accordance withthe invention.

FIG. 8 is a cross-section of a probe being mounted using the epoxygroove and probe alignment control element of the preferred embodimentof a test probe card assembly structure in accordance with theinvention.

FIG. 9 is a cross-section of probes being mounted in a multi-layeredmanner on the preferred embodiment of a test probe card assemblystructure in accordance with the invention.

FIG. 10 is an isometric view of the resulting test probe cardconstructed on the preferred embodiment of a test probe card assemblystructure in accordance with the invention.

FIG. 11 is a top plan view of probes attached to a test probe card madeon the preferred embodiment of a test probe card assembly structure inaccordance with the invention testing a square integrated circuit chipat different angles.

FIG. 12 is a cross-section of three probes held in place by an epoxylayer on the preferred embodiment of a test probe card assemblystructure in accordance with the invention.

FIG. 13A is an isometric view of a single-layer probe card with probeslocated in the same row constructed on the preferred embodiment of atest probe card assembly structure.

FIG. 13B is an isometric view of a multi-layered probe card with probeslocated in two rows constructed on the preferred embodiment of a testprobe card assembly structure.

FIG. 14 is a top view of a wafer which has finished chips.

FIG. 15 shows four chips arranged in a diagonal, which is the preferredarrangement for testing multiple chips.

FIG. 16 shows a top view of a multichip tester according to the presentinvention.

FIG. 17 shows a single section from the multichip tester of FIG. 16.

FIG. 18 shows a side view of the single section of FIG. 17.

FIG. 19 shows the probe arrangement for testing three chipssimultaneously.

FIG. 20 shows a probe positioning structure for making the multichiptester of the present invention.

FIG. 21 shows the probe positioning structure with probes attached.

FIG. 22 shows the probes and probe positioning structure with anadditional layer of epoxy applied.

FIG. 23 shows the probes and epoxy layer after separation from the probepositioning structure.

FIG. 24 shows the probes and epoxy layer attached to a circuit board tocomplete the probe card.

DETAILED DESCRIPTION

A preferred embodiment of the invention is shown in FIG. 10. Thefunction of a test probe assembly structure is to allow construction ofa test probe card which has probes arranged in a parallel manner andwith the same inclination angle so as to touch the contacts of anintegrated circuit chip directly, in the absence of fan out angles.Accordingly, the problem of uneven contact forces between probes andcontacts and the problem of the probe tip scrubbing across the contactonto the surface of the chip should be minimized. There will also beless chance of dislodging or deforming the Mylar sheath and the probetips. In addition, the inclusion of an epoxy groove to control epoxyflow should reduce misalignment of probes, as well as variances in beamlength of the probes.

A base 14 of test probe card assembly structure 10 is simply a piece ofmaterial of adequate size and strength to support construction of a testprobe card. In practice, a square planar base formed from a rigidmaterial is used.

A block 16 attached to a top side 12 of base 14 is used solely tosupport a sheath 18 for keeping probe tips 15 in place (see FIG. 7A).Block 16 may actually comprise any shape so long as it can support probetip sheath 18.

Also attached to top side 12 of base 14 are wings 20, which may numberfrom one to four. The purpose of wings 20 is to provide a surface onwhich to place probes 22 in a parallel manner and at a constantinclination angle so that probe tips 15 can touch the contacts of anintegrated circuit chip directly, without a fan out angle and withoutvariances in force between probe tips 22 and contacts of the IC chip.

Wings 20 can be constructed in two parts: a support structure 21 and aprobe positioning structure 24. Support structure 21 is attacheddirectly to base 14. It has a planar face which is inclined in thedirection of block 16. The incline should end at the same height andadjacent to block 16. Probe positioning structure 24 is attached to topside 12 of support structure 20. It comprises a planar face,theoretically with the same circumference as the planar face of supportstructure 20. Probe positioning structure 24 has an epoxy groove 26 ofpredetermined length and width into which epoxy 28 can be poured (seeFIG. 7A). Groove 26 is a recess which prevents epoxy 28 from flowing andthus causing misalignment of probes 22 and variance in beam length. Inaddition there is a tape groove 30 of predetermined length and width.Groove 30 is for placement of double-sided adhesive tape 32, which helpskeep probes 22 in place.

Square sheath 18, commonly constructed of Mylar, is placed on top side12 of block 16 and centered by two protruding pins (not shown). Sheath18 contains small holes 19 along its perimeter where probe tips 15 willbe placed. Mylar sheath 18 thus helps with the positioning of probes 22.Sheath 18 is not permanently attached to assembly structure 10. However,it is held in place by two part wing structure 20, specifically probepositioning structure 24. The result is that sheath 18 is fastenedbetween support structure 21 and probe positioning structure 24. Varioussheaths may be produced to satisfy the requirements of the probe cardbeing constructed.

A probe alignment control element 34, commonly a ring (see FIG. 6), isused to compress epoxy layer 28 poured over probes 22. It contains atleast one raised section 36 which contacts epoxy 28. In the constructionof a probe card to test a square IC chip with contacts along all foursides, there are four raised sections 36. Section 36 is often ridged toprovide better wetting of probe alignment control element 34 to epoxy28. Probe alignment control element 34 is placed over epoxy layer 28with raised section 36 corresponding in position with epoxy groove 26 ofprobe positioning structure 24. Probe alignment control element 34contains at least one recess 38, such as a small hole, located nearraised section 36, to fit with a guiding member 40, whose purpose is tohelp position probe alignment control element 34.

Guiding member 40 is commonly a pin attached perpendicular to top side12 of base 14 between adjacent wings 20 and near block 16. Guidingmembers 40 fit into the recesses of probe alignment control element 34,thus determining its placement relative to epoxy groove 26 and epoxy 28a. A stopping member 42 is also commonly a pin attached perpendicular totop side 12 of base 14 between adjacent wings 20 and near block 16.Stopping members 42 prevent probe alignment control element 34 fromcompressing epoxy layer 28 too far, thus determining its height relativeto epoxy groove 26 and epoxy layer 28.

Test probe assembly structure 10 can be constructed with guidingmechanisms 44, 46 to allow movement of wings 20, guiding members 40, andstopping members 42 relative to each other. Guiding mechanisms 44, 46are built into top side 12 of base 14 and operate much like slits, inthat they allow different components 20, 40, 42 to be slid along base14. However, any type of adjustable mechanism is feasible. Thus, it ispossible that several different probe cards could be constructed on asingle test probe assembly.

Construction of a Single-Layered Probe Card

Test probe card assembly structure 10 should be set up according to thespecifications of the desired test probe card to be produced. Inpractice, all four wings 20 and at least two guiding members 40 will beused to construct the typical probe card used to test a square IC chipwith contacts located on the perimeter. Suitable Mylar sheath 18 withthe appropriate pattern of holes 19 for probe tips 15 is chosen andplaced on top side 12 of block 16. Mylar sheath 18 may be secured inplace by the use of two-structure wing 20, which allows probepositioning structure 24 to be placed over the edges of sheath 18 andfastened.

Epoxy 28 is poured into epoxy grooves 26 of wings 20 and allowed to curefor a few minutes. This curing helps prevent epoxy 28 from flowingaround probes 22 when they are placed on planar face of wings 20. Piecesof double-sided adhesive tape 32 are placed in tape grooves 30. Probes22 are then placed on wings 20, over epoxy grooves 26 and tape grooves30, in a parallel manner and at a constant inclination angle, with probetips 15 pointing down the inclines toward block 16. Probe tips 15 shouldfit into Mylar sheath 18 which has been placed on block 16. If all fourwings 20 are used, probes 22 will form a square or rectangle, with probetips 15 in each row positioned essentially parallel to each other and ata constant inclination angle.

It is noted that although epoxy is the preferred adhesive material touse in the present invention, many other hard-setting, electricallyinsulating liquid adhesives can be used. Polyester resins, for example,may be useful in some embodiments of the present invention.

Another layer of epoxy 28 is poured over probes 22, thereby securingthem in place. Probe alignment control element 34 is then placed overepoxy 28, eased into place by guiding members 40 and stopping members42. Guiding members 40 and stopping members 42 control the position andheight of probe alignment control element 34 so that it compresses epoxylayer 28 according to the specifications of the test probe card beingmade. Raised sections 36 of probe alignment control element 34 contactepoxy layer 28 to form a secure attachment. Probe alignment controlelement 34 stays attached to epoxy layer 28 and probes 22. After epoxylayer 28 is hardened, the probe-epoxy structure is fastened to a planarprinted circuit board 48.

Construction of a Multi-Layered Probe Card

Construction of a multi-layered test probe card can also be achieved ontest probe card assembly structure 10. Setup of test probe assemblystructure 10 for a multi-layered test probe is essentially the same asthat for a single-layered test probe. In practice, all four wings 20 andat least two guiding members 40 will be used to construct the typicalprobe card used to test a square IC chip with contacts located in one ormore rows on one side of the chip. Suitable Mylar sheath 50 with theappropriate pattern of holes 19 for probe tips 15 is chosen and placedon top side 12 of a block 16 for accommodating tips 15. If one isconstructing a multi-layered probe card with one row of probes 22located on two levels, the Mylar sheath 18 will have one row of holes 19(see FIG. 13A). If one is constructing a multi-layered probe card withat least two rows of probes 22 located on two levels, there will be atleast two rows of holes 19 on Mylar sheath 50 (see FIG. 13B). Mylarsheath 50 may be secured in place by the use of two-structure wing 20,which allows probe positioning structure 24 to be placed over the edgesof sheath 50 and fastened.

The first layer of probes 22 is positioned and secured in much the samemanner as described above for the single-layered probe card. However,after epoxy layer 28 is poured over probes 22, probe alignment controlelement 34 is not placed on top. Epoxy layer 28 is allowed to cure for acertain amount of time, much like first epoxy layer 28 poured intogroove 26.

Spacer elements or another layer of double-sided adhesive tape 52 arethen placed over the first layer of probes 22. Spacer elements oranother layer of double-sided adhesive tape 52 are shorter in lengththan probe positioning structure 24 and do not contain epoxy groove 26.This is because the second layer of probes 22 will be placed in epoxylayer 28 that was poured over the first layer of probes 22. Spacerelements or another layer of double-sided adhesive tape 52 are supportedby the edges of probe positioning structure 24.

The second layer of probes 22 is placed on spacer elements or anotherlayer of double-sided adhesive tape 52. Probes 22 are positioned in aparallel manner and in the same plane. Probe tips 15 are positioned inthe remaining empty holes 19 of Mylar sheath 50. Probes 22 are placed onepoxy layer 28 that was poured over the first layer of probes 22. Athird layer of epoxy 28 is then added over the second layer of probes 22to secure them in place. This third epoxy layer 28 is added over theprevious epoxy layers 28.

At this point, it is possible to keep adding probe 22 and epoxy layers28, although practical considerations suggest a maximum of layers asdefined by the nature of the probe card to be constructed.

Probe alignment control element 34 used to construct the single-layeredprobe card is then placed over the epoxy 28, eased into place by guidingmembers 40 and stopping members 42 in the same manner as describedpreviously. Probe alignment control element 34 stays attached to epoxylayer 28 and probes 22. After epoxy layer 28 is hardened, themulti-layered probe-epoxy structure is fastened to planar printedcircuit board 48 just like the single-layered probe.

Some example types of probe cards which can be constructed on assemblystructure 10 or any analogous structure according to the invention areshown in FIGS. 13A and 13B. FIG. 13A illustrates a straight section of asingle-layer probe card. The inclination angles β of all three probes 22shown are equal. Also, fan out angle θ of probes 22 is approximatelyzero. These conditions improve planarity and uniformity of contact forcebetween probe tips 15 and circuit pads 106. This is important because inpractice probes 22 frequently require post-production tweaking orbending to ensure planarity. With angles θ and β being constant theamount of tweaking required is minimized. Epoxy 28 is prone to damageduring a tweaking session and its life is thus prolonged when the amountof tweaking required is reduced.

FIG. 13B shows a straight section of a dual-layered probe card madeaccording to the invention. Once again, angles θ and β are controlled inthis card.

A Probe Card for Simultaneously Testing Multiple Chips

An embodiment of the present invention can make probe cards capable oftesting multiple chips simultaneously. FIG. 14 shows a wafer 60comprising finished chips. The chips to be tested 62 are arranged alonga diagonal of the wafer. This is because the contact pads on each chip62 are distributed along the entire perimeter of each chip. Selectingchips to be tested along a diagonal assures access to every contact pad.If the chips are arranged in a rectangular block 64, and the contactpads are located around the perimeter of each chip, then probe access tosome contact pads is difficult or impossible.

FIG. 15 shows a closeup of the four chips 62 along a diagonal. Thecontact pads 66 on each chip are shown. It can be seen that the contactpads 66 are arranged in two zig zag paths.

FIG. 16 shows a top view of a probe card capable of testing multiplechips 62. The probes 22 are arranged to make contact with the contactpads 66. The probes 22 are held in place by an epoxy layer 28. Since theedge 68 of the epoxy layer 28 is a zig zag shape, the beam length(distance from contact pad 66 to epoxy layer edge 68) of each probe 22is identical.

FIG. 17 shows a single section of a probe card capable of testingmultiple chips. The section shown can only test a single chip 62, butseveral sections can be combined in a line to produce a probe card thatcan test several chips. All the probes 22 are inclined with the sameangle β with respect to the surface of the chip 62 being tested. Angle βis typically about 10 degrees.

FIG. 18 shows a side view of the section of FIG. 17 without the epoxylayer 28. Here, the angle β is clearly visible.

FIG. 19 shows a perspective view of three sets of probes 22 contactingthree chips 62. The epoxy layer 28 which holds the probes 22 is notshown. It can be seen that the probes 22 are arranged in a corrugatedpattern so that β and the beam length are the same for every probe 22even though the contact pads 66 lie along a zig zag path. Also, theprobe tips lie in he same plane. The corrugated pattern is illustratedwith a dark line 70.

Refer now to FIG. 20. The multichip probe of the present invention canbe made using a pair of probe positioning structures 24 with eachstructure having a corrugated top 72 that is also inclined at the angleβ. The probe positioning structures 24 are mounted on a base 12 facingeach other in a symmetrical fashion. The base 12 is omitted insubsequent figures. The corrugated top 72 is comprised of adjacentopposing surfaces 74A, 74B. The corrugation angles ω₁ and ω₂ aredetermined by the shape of the chips 62 to be tested and the angle β.Angles ω₁, and ω₂ are selected such that every probe 22 has the samebeam length and same orientation with respect to its correspondingcontact pad 66. For square chips, for example, ω₁ and ω₂ will be thesame for opposing surfaces 74A, 74B of the corrugated surface of thesupport structure. In the case of testing rectangular chips, ω₁ and ω₂will be different for the different opposing top surfaces 74A, 74B ofthe corrugated probe positioning structures 24. More specifically, thisresults in ω₁ and ω₂ being different angles.

The first step in the manufacture of a multichip probe according to thepresent invention is shown in FIG. 21. The probes 22 are placed andbonded to the top surface 72 of the corrugated probe positioningstructures in the same manner as described for the construction of asingle-layered probe card. Specifically, double-sided tape and epoxy arepreferably used to secure the probes 22 to the structures 24 and a mylarsheath 18 with small holes is used to align the probe tips 15. The topsurface of the probe positioning structure 24 may have an epoxy grooveand tape groove as illustrated in FIGS. 7, 8, and 9. Only three of thefour sections of the support structures of FIG. 21 are provided withprobes in order to more clearly illustrate the process.

Next (FIG. 22), an additional layer of epoxy 28B is applied on top ofthe probes 22 to rigidly hold them with respect to one another. Thealignment control element 34 (not shown) can be used to maintain thealignment between the two sides of probes 22. The use of the alignmentcontrol element 34 in the manufacture of a multichip probe card is thesame as described for the single-layered probe card of FIG. 10. Thecontacting surface of the alignment control element 34 may need to becorrugated so that it contacts all the probes 22.

The probes 22 and epoxy layer 28 are then separated from the probepositioning structures 24. FIG. 23 shows the probes 22 and epoxy layer28 after separation. It can be seen that the probes 22 define acorrugated plane. The corrugated plane defined by the probes 22 is thesame as the top surface 72 of the probe positioning structures 24. Thealignment control element 34 is used to hold the two sides of probesfixed with respect to one another. Alternatively, rigid metal connectors78 can be used to hold the two sides fixed with respect to one another.

The probes 22 and epoxy layer 28 structure of FIG. 23 is then inverted(flipped over) and bonded to a printed circuit board 48 to produce theprobe card shown in FIG. 24. The probe tips 15 thus point upwards inFIG. 24. Extra epoxy is applied to further secure the alignment of theprobes 22. Alternatively, any thin, rigid plate can be used in place ofa printed circuit board. Electrical connections can be made to the probeends 76 which extend through the epoxy layer 28.

It is noted that the probes 22 used in the present invention do notnecessarily need to have a bent tip section 15. In other words, theprobes 22 may comprise sraight wires. Using straight wire probes may, ofcourse, require a different angle β.

It will be clear to one skilled in the art that the above embodiment maybe altered in many ways without departing from the scope of theinvention. For example, different shapes of integrated circuit chips canbe accommodated by this invention. If one has an integrated circuit chipin the shape of a triangle with circuits located on the perimeter, atest probe card can be constructed whereby three rows of probes arearranged in a triangular shape. The assembly structure for such a probecard would consist of three wings arranged around a triangular block,with a triangular Mylar sheath. Thus many different shapes of IC chipscan be accommodated.

It is also noted that many different glues or resins (more generallyadhesives) can be used other than epoxy. Whatever material is used inplace of epoxy in the present invention must be a electricallyinsulating material that is hard, resistant to repeated flexing cyclesand curable from a liquid state. Epoxy is the preferred material to usein the present invention because it is easy to use, is strong and isnon-conductive.

In addition, it should be noted that in cases where many probes areplaced in a single row, a small fan out angle θ may still exist.However, this angle θ will be essentially negligible. Accordingly, thescope of the invention should be determined by the following claims andtheir legal equivalents.

What is claimed is:
 1. A probe card for simultaneously contactingcontact pads being positioned in a zig zag path along a perimeter of aplurality of integrated circuit chips, said integrated circuit chipsbeing arranged along a diagonal axis, said probe card comprising: A) aplurality of substantially parallel linear probes having a tip forcontacting said contact pads; B) a structure for fixedly holding saidprobes, said structure comprising: I) a corrugated surface havingindividual surfaces corresponding to a projection of said zig zag pathalong a nonzero angle β, each of said individual surfaces fixedlyholding at least one of said probes such that said tips are positionedcorrespondingly to said zig zag path; II) an edge correspondingly shapedto said zig zag path such that said plurality of probes havesubstantially equal beam lengths.
 2. The probe card of claim 1, whereinsaid probes are attached to said corrugated surface with an epoxy layer.3. The probe card of claim 1, wherein said individual surfaces form anarray of alternatingly opposing planar surfaces corresponding to anumber of first parallel lines alternating with a number of secondparallel lines, said first parallel lines and said second parallel linesbeing part of said zig zag path.
 4. The probe card of claim 1, whereinsaid integrated circuit chips are attached in the form of a wafer. 5.The probe card of claim 1, further comprising a sheath with a pluralityof holes for aligning said probes.